This invention is in the field of wheelbarrows and carts. In particular, it concerns apparatus for converting a wheelbarrow into a cart and a cart including such apparatus.
Wheelbarrows are widely used devices for transporting loads, particularly in construction and gardening. A wheelbarrow generally has a front wheel, handles that extend rearward, and legs beneath the handles. In use, the wheelbarrow stands on the front wheel and the legs. To transport a load, a user grasps the pair of handles and lifts so that part of the load is carried by the front wheel and part of load is carried by the user's arms. A moving wheelbarrow relies on the user's balance and strength to support its upright orientation.
The load that a wheelbarrow can accommodate is in part limited by the size of the tray, but it is also limited by the arm strength of the user. Large-tray wheelbarrows find wide use in construction jobs, but home-use wheelbarrows are typically smaller to accommodate occasional users who may lack the strength needed to transport larger loads. Thus there is a need for wheelbarrows that can accommodate large or heavy loads without requiring great strength and exertion by the user. Because wheelbarrows are in common use, there is also a need for a conversion kit to modify a conventional wheelbarrow for use without requiring high exertion.
A wheelbarrow is useful in part because it can be easily steered. Handgrips at the ends of relatively long handles allow a user to apply a long moment arm to alter the course even though the wheel itself is usually on a fixed axis. The single wheel design limits contact with the ground to a small area so that resistance to course change is relatively low. Thus, in order to maintain utility of a wheelbarrow, any cart conversion needs to retain the ability for the user to steer the converted wheelbarrow.
A conventional wheelbarrow has a three-point stance between the front wheel and the pair of rearward mounted legs. Large capacity wheelbarrows are known to tip over, particularly during filling. Thus in order to maintain stability of a wheelbarrow, any cart conversion needs to maintain, and preferably increase, the spacing and stability of supports.
Paired handles are present in conventional wheelbarrows to lift the load for transport. However, such handles are difficult to use in a cart. There is thus a need for a cart including a handle that permits a converted wheelbarrow to be pushed, pulled, or steered.
Others have addressed these problems with only partial success. U.S. Pat. No. 6,880,852 to Lim teaches a wheelbarrow that has both an added handle and added rear wheels. The wheels run on a fixed axle attached to the wheelbarrow legs and thus are not easily steerable. U.S. Pat. No. 6,220,622 to Garcia includes pivoting wheels attached to individual posts depending from the respective handle. U.S. Pat. No. 6,508,478 to Ortez also shows pivoting wheels. Ortez attaches the wheels (and a toolbox) to the existing legs of the wheelbarrow and spaces the wheels wider than the legs. The Ortez toolbox anchors the wheels behind the wheelbarrow legs, thus shifting the load supports away from the filled-tray center of mass. Both Lim and Ortez teach attachment of wheels to wheelbarrow legs, so that the legs remain in place but do not contact the ground. The dangling legs add weight without function and also interfere with the wheel placement so that the modified wheelbarrow necessarily stands higher than the unmodified wheelbarrow, complicating loading and limiting capacity because the top edge of the tray is no longer level when standing on level ground.